What is the most significant learning from the failed product launch?

Identify users who are ready to pay before developing your product.

How do you define a Failure or Success first? I launched Glibzter Immersive - English Vocabulary Builder on 19th December (a Thursday) competing with 183 products and ending up unfeatured at a credible #24. 61 landing page visitors, 2 converted users. All this with a hunter who backstabbed us by not showing up! The learning: Unless you have a hunter of repute or users/ partners who are willing to go the distance to create PH accounts and upvote, it is injudicious to launch a product on Tuesday, Wednesday or Thursday.

Definitely don't build something until you've validated there are paying customers for it. Do user interviews, get letters of intent to purchase, even pre-sell before writing a line of code if you can. It's way too easy to assume people will pay for your product, only to find out after building it that they actually won't. Painful lesson many of us have learned the hard way!